Alloy



Patented- Oct. 20, 1942 ALLOY Cecil Spencer Slvll. Roselle, and Edward 0. Liebig,

North Arlington, N. 1., assignors to Baker &

Company, Inc., Newark, N. J., a; corporation of New Jersey .No Drawing. Application December 19, 1941, Serial No. 423,601

5Claims. (Cl. 15-1-12) This invention relates to alloys and is concerned in particular with precious metal alloys.

It is one object oi our invention to provide an alloy having the color and general appearance of platinum and having a, high degree of resistance to corrosion and oxidation. It is another object of our invention to-provid analloy oi the type described, which'shall have great hardness and tensile strength combined with great ductility.

In our Patent No. 2,189,571, granted February 6, 1940, we have described alloys of 20% to 60% platinum, 10% to 40% palladium, 10% t 50% silver, and 1% to 25% gold. Such alloys are resistant to corrosion and oxidation and have high tensile strength and hardness; and possess sufficient ductility so that they can be-easily worked mechanically into suitable shapes. In the continuation of our research of quaternary alloys .of platinum, palladium, silver, and gold, in the search for alloys of greatte'nsile strength and hardness combined with high ductility, we have found that a surprisingly advantageous alloy can be produced outside the range of our aforesaid patent by decreasing the content of silver to less than 10% and, likewise, varying the proportional contents of the other three constituents.

The following table illustrates some of the properties of our new alloys:

Composition, per cent I g??? Pm 3 Elongation Pt Pd All Ag Lila/sq. in... Lbal In. l ar cent v 50 22 20 8 155,10 148%00 12 50 26 20 4 181, 51X) 151, 000 14. 5 28. 20 2 118, 132,000 12 It will be noted that one prime distinction between our new alloys and those of our Patent No. 2,189,571 is the lower silver content. In properties, our new alloys. are, likewise, distinguished 'irom..our previous alloys in that the tensile strength is considerably increased without a corresponding decreas in elongation, i. e. ductility,

and that on the contrary there appears a tendency toward an increase in ductility combined with an increase in tensile strength. An alloy of 60% platinum, 20% palladium, gold, and 10% silver, representing in its silver content the lower limit of our previous alloy, has a tensfle strength 0! only 139,000 lbs. per sq.in., and

a proportional limit of 123,000 lbs. per sq. in. combined with an elongation of 12%. On the other in properties from ternary alloys of platinum,

palladium, and gold, 1. e. alloys without silver, in

. that they have considerably greater tensile strength; an alloy, for instance, of 50% platiproportional limit of 80,000 lbs. per sq.'in. with an elongation oi 13%.

The alloys according to this invention contain from 40% to 60% platinum, from to 40% palladium, from 10% to gold, and 1% to less than. 10% silver. The dividing line of 10% silver between our previous alloys and our new alloys is critical in combination with a higher minimum content of platinum, palladium and gold, as compared with our previous alloys, in order to obtain the greatly increased tensile strength combined with high or even higher ductility.

Likewise, alloys containing less than 1% silver do' not appear to possess the properties characteristic of the quaternary alloys here involved, but

possess on the contrary the general properties or the comparable ternary alloys. It will be noted that, in the alloys 01' the table above given, there is obtaineda definite peak in the alloy of 50% platinum, 26% palladium, 20% gold and 4% silver, with the tensile strength tapering oii with an increase of silver as well as with a decrease of silver. In the triangle thus formed, with the ferred range or our new alloys would contain on the one slope a minimum of 2% silver and on the other slope acomparable maximum of 9% would correspond to an alloy of 2.75% silver on thepther slope- Likewise, the preferred range of such alloys should contain a minimum of about 60% platinum and gold combined, as well as a minimum of about 61% platinum and palladium combined.

. above table, for instance, all have a melting point in excess of 2732 F. The hardness of our new alloys, likewise, is in excess of that of other quaternary alloys as is also their. resistance to cor- I rosion and oxidation. The alloys are completely resistant to acids, such as hydrochloric acid, nitric acid, Sulphuric acid,- etc. The new alloys'also retain their hardness at elevated temperatures as their softening point is extremely high.

The alloys according to this in'vention'are suitable ior many uses and areparticularly suitable for the manufacture of dental appliances subject hand, our new alloys are, likewise, distinguished to corrosive or the like influences, such as dentufes, orthodontia wires, clasps, etc. The alloys 3. An alloy of platinum. palladium, gold and are, likewise, suitable tor Jewelry and the like silver composed o! 40% to 60% platinum, 20% purposes. a to 40% palladium, to 30% gold, and about What we claim is: 4% silver.

1. An alloy of 40% to 60% platinum, to 5 4. An alloy of about 50% platinum, about 26% 40% palladium, 10% to gold, and 2% to 9% palladium, about 20% gold, and about 4% silver. silver. 5. An alloy of platinum, palladium, gold and l 2. An alloy of to 60% platinum, 20% to silver composed or about platinum, about 40% palladium, 10% to 30% gold, and 2% to 9% 20% gold, from 22% to 28% palladium, and 1mm silver, wherein the combined content of platinum 10 2.75% to 8% silver. and gold is not. less than about and the CECIL B. BIVIL. combined content of platinum and palladium is EDWARD O. LlEBIG. not less than about 61%. 

